Hydrocarbon conversion with a multimetallic catalytic composite

ABSTRACT

Hydrocarbons are converted by contacting them at hydrocarbon conversion conditions with a trimetallic acidic catalytic composite comprising a combination of catalytically effective amounts of a platinum group component, a rhenium component, a bismuth component and a halogen component with a porous carrier material. The platinum group component, rhenium component and halogen component are present in the trimetallic catalyst in amounts respectively, calculated on an elemental basis, corresponding to about 0.01 to about 2 wt. percent platinum group metal, about 0.01 to about 2 wt. percent rhenium and about 0.1 to about 3.5 wt. percent halogen. The bismuth component is present in amounts corresponding to an atomic ratio of bismuth to platinum group metal of about 0.1:1 to about 1:1. Moreover, these metallic components are uniformly dispersed throughout the porous carrier material in carefully controlled oxidation states such that substantially all of the platinum group metal, rhenium and bismuth components are present therein in the corresponding elemental metallic states. A specific example of the type of hydrocarbon conversion process disclosed is a process for the catalytic reforming of a low-octane gasoline fraction wherein the gasoline fraction and hydrogen stream are contacted with the novel trimetallic catalyst disclosed herein at reforming conditions.

United States Patent 1 Wilhelm Jan.7, 1975 Frederick C. Wilhelm,Arlington Heights, 111.

[73] Assignee: Universal Oil Products Company, Des Plaines, 111.

[22] Filed: Feb. 4, 1974 [21] Appl. No.1 439,477

Related US. Application Data [631 Continuation-in-part of Ser. No.233,819, March 10.

1972, Pat. NO. 3,798,155.

[75] Inventor:

[52] US. Cl 208/139, 208/111, 260/683.68, 252/441 [51] Int. Cl..... C10g35/08, C10g 13/10, C070 5/30 [58] Field of Search 208/138, 139, 111;260/683.68', 252/441 [56] References Cited UNITED STATES PATENTS3,156,737 11/1964 Gutberlet 260/683.65 3,206,391 9/1965 Gutberlet et a1208/108 3,291,755 12/1966 Haensel et a1. 260/6833 3,511,888 5/1970Jenkins 208/138 3,558,479 l/l97l Jacobson et al. 208/139 3,651,1623/1972 Pohlmann et a1. 260/672 T 3,651,163 3/1972 Radford et a1 208/139Primary Examiner-Delbert E. Gantz Assistant ExaminerJames W. HellwegeAttorney, Agent, or Firm-James R. Hoatson, Jr.; Thomas K. McBride;William H. Page, 11

[57] ABSTRACT Hydrocarbons are converted by contacting them athydrocarbon conversion conditions with a trimetallic acidic catalyticcomposite comprising a combination of catalytically effective amounts ofa platinum group component, a rhenium component, a bismuth component anda halogen component with a porous carrier material. The platinum groupcomponent, rhenium component and halogen component are present in thetrimetallic catalyst in amounts respectively, calculated on an elementalbasis, corresponding to about 0.01 to about 2 wt. percent platinum groupmetal, about 0.01 to about 2 wt. percent rhenium and about 0.1 to about3.5 wt. percent halogen. The bismuth component is present in amountscorresponding to an atomic ratio of bismuth to platinum group metal ofabout 0.1:] to about 1:1. Moreover, these metallic components areuniformly dispersed throughout the porous carrier material in carefullycontrolled oxidation states such that substantially all of the platinumgroup metal, rhenium and bismuth components are present therein in thecorresponding elemental metallic states. A specific example of the typeof hydrocarbon conversion process disclosed is a process for thecatalytic reforming of a low-octane gasoline fraction wherein thegasoline fraction and hydrogen stream are contacted with the noveltrimetallic catalyst disclosed herein at reforming conditions.

16 Claims, No Drawings HYDROCARBON CONVERSION WITH A MULTIMETALLICCATALYTIC COMPOSITE CROSS-REFERENCES TO RELATED APPLICATIONS Thisapplication is a continuation-in-part of my prior application Ser. No.233,819 filed Mar. 10, 1972, now US. Pat. No. 3,798,l55 all of theteaching of which are specifically incorporated herein by reference.

The subject of the present invention is a novel acidic trimetalliccatalytic composite which has exceptional activity, selectivity andresistance to deactivation when employed in a hydrocarbon conversionprocess that requires a catalyst having both ahydrogenationdehydrogenation function and a selective acid or crackingfunction. More precisely, the present invention involves a noveldual-function acidic trimetallic catalytic composite which beneficiallyutilizes a catalytic component, bismuth, which traditionally has beenthought of and taught to be a poison for a platinum group metal becauseof its close proximity in the Periodic Table to the notorious platinumpoison, arsenic. Bismuth is utilized in the present invention tointeract with a platinum group metaland rhenium-containing acidiccatalyst to enable substantial improvements in hydrocarbon conversionprocesses of the type that have traditionally utilized platinum groupmetalcontaining catalysts to accelerate the various hydrocarbonconversion reactions associated therewith. In another aspect thisinvention concerns the improved process that are produced by the use ofan acidic trimetallic catalytic composite comprising a combination of aplatinum group component, a rhenium component, a bismuth component, anda halogen component with a porous, high surface area carrier material ina manner such that l) the platinum group, bismuth and rhenium componentsare uniformly dispersed throughout the porous carrier material, (2) theamount of the bismuth component is not greater than the amount of theplatinum group component on an atomic basis, and (3) substantially allof the platinum group, rhenium and bismuth components are presenttherein as the corresponding metals. In a specific aspect, the presentinvention concerns an improved reforming process which utilizes thesubject acidic trimetallic catalyst to markedly improve activity,selectivity and stability characteristics associated therewith, toincrease yields of C reformate and of hydrogen recovered therefrom andto allow operation thereof at high severity conditions not heretoforegenerally employed in the art of continuous catalytic reforming ofhydrocarbons with a platinumcontaining monometallic, dual-functioncatalyst.

Composites having a hydrogenationdehydrogenation function and aselective acid or cracking function are widely used today as catalystsin many industries, such as the petroleum or petrochemical industry, toaccelerate a wide spectrum of hydrocarbon conversion reactions.Generally, the cracking function is thought to be associated with anacid-acting material of the porous, adsorptive, refractory oxide typewhich is typically utilized as the support or carrier for a heavymetallic component such as the metals or compounds of metals of thetransition elements of Groups V through VIII of the Periodic Table towhich are generally attributed the hydrogenationdehydrogenationfunction.

These catalytic composites are used to accelerate a wide variety ofhydrocarbon conversion reactions such as hydrocracking, isomerization,dehydrogenation, hydrogenation, desulfurization, cyclization,alkylation, polymerization, halogenation, hydrogenolysis, cracking,hydroisomerization, etc. In many cases, the commercial applications ofthese catalysts are in processes where more than one of these reactionsare proceeding simultaneously. An example of this type of process isreforming wherein a hydrocarbon feed stream containing paraffins andnaphthenes is subjected to conditions which promote dehydrogenation ofnaphthenes to aromatics, dehydrocyclization of paraffins to aromatics,isomerization of paraffins and naphthenes, hydrocracking of napthenesand paraffins, and the like reactions to produce an octane-rich oraromatic-rich product stream. Another example is a hydrocracking processwherein catalysts of this type are utilized to effect selectivehydrogenation and cracking of high molecular weight unsaturatedmaterials, selective hydrocracking of high molecular weight materials,and other like reactions to produce a generally lower boiling, morevaluable output stream. Yet another example is a hydroisomerizationprocess wherein a hydrocarbon fraction which is relatively rich instraight-chain paraffin and/or olefinic compounds are contacted with adual-function catalyst to produce an output stream rich in isoparaffincompounds.

Regardless of the reaction involved or the particular process involved,it is of critical importance that the dual-function catalyst exhibit notonly the capability to initially perform its specified functions butalso that it has the capability to perform them satisfactorily forprolonged periods of time. The analytical terms used in the art tomeasure how well a particular catalyst performs its intended functionsin a particular hydrocarbon reaction environment are activity,selectivity and stability. And for purposes of discussion here theseterms are conveniently defined for a given charge stock as follows: (1)activity is a measure of the catalysts ability to convert hydrocarbonreactants into products at a specified severity level where severitylevel means the reaction conditions used that is, the temperature,pressure, contact time, and presence of diluents such as H (2)selectivity refers to the amount of desired product or products obtainedrelative to the amount of reactants converted or charged; (3) stabilityrefers to the rate of change with time of the activity and selectivityparameters obviously, the smaller rate implying the more stablecatalyst. n a reforming process, for example, activity commonly refersto the amount of conversion that takes place for a given charge stock ata specified severity level and is typically measured by octane number ofthe C product stream; selectivity usually refers to the amount of Cyield that is obtained at the particular severity or activity levelrelative to the amount of the charge stock; and stability is typicallyequated to the rate of change with time of activity, as measured byoctane number of C product and of selectivity, as measured by C yield.Actually, this last statement is not strictly correct because generallya continuous reforming process is run to produce a constant octane C,+product with a severity level being continuously adjusted to attain thisresult; and, furthermore, the severity level is for this process usuallyvaried by adjusting the conversion temperature in the reaction zone sothat, in point of fact, the rate of change of activity finds response inthe rate of change of conversion temperatures and changes in this lastparameter are customarily taken as indicative of activity stability.

As is well known to those skilled in the art, the principal cause ofobserved deactivation or instability of a dual-function catalyst when itis used in a hydrocarbon conversion reaction is associated with the factthat coke forms on the surface of the catalyst during the course of thereaction. More specifically, in these hydrocarbon conversion processes,the conditions utilized typically result in the formation of heavy, highmolecular weight, black, solid or semi-solid, carbonaceous materialwhich coats the surface of the catalyst and reduces its activity byshielding its active sites from the reactants. In other words, theperformance of this dual-function catalyst is sensitive to the presenceof carbonaceous deposits on the surface of the catalyst. Accordingly,the major problem facing workers in this area of the art is thedevelopment of more active and selective catalytic composites that arenot as sensitive to the presence of these carbonaceous materials and/orhave the capability to suppress the rate of formation of thesecarbonaceous materials on the catalyst. Viewed in terms of performanceparameters, the problem is to develop a dual-function catalyst havingsuperior activity, selectivity and stability. In particular, for areforming process the problem is typically expressed in terms ofshifting and stabilizing the C yield-octane relationship C yield beingrepresentative of selectivity and octane being proportional to activity.

I have now found a dual-function catalytic composite which possessesimproved activity, selectivity, and stability when it is employed in aprocess for the conversion of hydrocarbons of the type which haveheretofore utilized dual-function catalytic composites such as processesfor isomerization, hydroisomerization, dehydrogenation, desulfurization,denitrogenization, hydrogenation, alkylation, dealkylation,transalkylation, cyclization, disproportionation, polymerization,oligomerization, hydrodealkylation, dehydrocyclization, cracking,hydrocracking, reforming, hydrogenation, halogenation, and the likeprocesses. In particular, I have ascertained that an acidic trimetalliccatalytic composite comprising a combination of a platinum groupcomponent, a bismuth component, a rhenium component and a halogencomponent with a porous, refractory carrier material can enable theperformance of a hydrocarbon conversion process utilizing adual-function catalyst to be substantially improved, provided theamounts and oxidation states of the metallic components and thedistribution thereof in the catalytic composite are care fullycontrolled in the manner indicated herein. Since the earliestintroduction of catalysts containing a platinum group component, it hasbeen axiomatic that the effect of arsenic on a platinum-containingcatalyst is detrimental. This concept has become so fixed and certain inthe artv that tremendous efforts have been devoted to removing arseniccontaminants from charge stocks that are to be processed in a unitcontaining a platinum catalyst. In addition, the art is replete with asignificant number of methods for reactivating a platinum-containingcatalyst once it has been deactivated by contact with arsenic orcompounds of arsenic. Because bismuth is a member of the same group ofthe Periodic Table (Group VA) and is known to have similar chemicalproperties to arsenic, it has fallen into the same category and has beentraditionally thought of as a poison for a platinum-containing catalyst.The art has an occasion hinted at or proposed to use the poisoningeffect of Group VA metallic elements to modify or attenuate the platinumcomponent of a'dual-function catalyst. For examples of thesesuggestions, reference may be had to the teachings of US. Pat. Nos.3,156,737; 3,206,391; 3,291,755 and 3,511,888. However, the art has notrecognized that bismuth can be utilized to promote a platinum-containingcatalyst; that is, to simultaneously increase its activity, selectivityand stability in hydrocarbon conversion service. In particular, the arthas apparently never contemplated the use of a platinum-bismuth catalystin a catalytic reforming process. As a matter of fact, the art on thislast process is replete with teachings that contact of theplatinum-containing reforming catalyst, with metallic elements of GroupVA of the Periodic Table, and particularly arsenic, is to be avoided ifat all possible and if contact occurs to any substantial degree thecatalyst must be immediately regenerated or reactivated by proceduresfor removal of these detrimental Group VA constituents. ln sharpcontrast to this historic teaching of the art that bismuth isdetrimental to a platinum-containing reforming catalyst, l have nowdiscerned that the presence of bismuth in a catalyst containing aplatinum group component and a rhenium component can be very beneficialunder certain conditions. One essential condition associated with theacquisition of the beneficial aspects of bismuth with this type ofplatinum-containing catalyst is the atomic ratio of bismuth to platinumgroup metal contained in the composite; my finding here indicate that itis only when this ratio is not greater than lzl that the beneficialinteraction of bismuth with a platinum group metal and rhenium isobtained. A second condition is the presence of a halogen component; myfinding on this matter is that the presence of a relatively small amountof halogen is required to see the beneficial effect. Another conditionfor achieving this beneficial interaction of bismuth with this type ofcatalyst is the distribution of the bismuth, rhenium and platinum groupmetal components in the carrier material with which they are combined;my finding here is that it is essential that these components beuniformly dispersed throughout the porous carrier material that is, theconcentration of these components is approximately the same in anyreasonably divisible portion thereof. Still another condition for thisbeneficial effect is the oxidation states of the metallic components; myfinding here is that it is essential that the bismuth, rhenium andplatinum group metal are present in the composite in the correspondingelemental metallic states. A trimetallic acidic catalyst meeting theseessential limitations differs sharply both in substance and incapabilities from the bismuthand platinum-containing catalyst that aresuggested by the prior art.

In the case of a reforming process, one of the principal advantagesassociated with the use of the instant acidic trimetallic catalystinvolves the acquisition of the capability to operate in a stable mannerin a high severity operation; for example, a continuous reformingprocess producing a C reformate having an octane of about I00 F-l clearand utilizing a relatively low pressure of 50 to about 350 psig. In thislatter embodiment the principal effect of the bismuth component is tostabilize the platinum group component by providing a mechanism forallowing it to better resist the rather severe deactivation. normallyassociated with these conditions. In short, the present inventionessentially involves the finding that the addition of a controlledamount of a bismuth component to a dual-function hydrocarbon conversioncatalyst, containing a platinum group component, a rhenium component anda halogen component, coupled with the uniform distribution of thebismuth component throughout the catalytic composite to achieve anatomic ratio of bismuth to platinum group metal of not greater than 1:1and with careful control of the oxidation states of the metalliccomponents enables the performance characteristics of the catalyst to besharply and materially improved.

It is, accordingly, one object of the present invention to provide anacidic trimetallic hydrocarbon conversion catalyst having superiorperformance characteristics when utilized in a hydrocarbon conversionprocess. A second object is to provide an acidic trimetallic catalysthaving dual-function hydrocarbon conversion performance characteristicsthat are relatively insensitive to the deposition of hydrocarbonaceousmaterial thereon. A third object is to provide preferred methods ofpreparation of this trimetallic catalytic composite which insures theachievement and maintenance of its beneficial properties. Another objectis to provide an improved reforming catalyst having superior activity,selectivity and stability when employed in a low pressure reformingprocess. Yet another object is to provide a dual-function hydrocarbonconversion catalyst which utilizes a relatively inexpensive component,bismuth, to promote and stabilize a platinum group metal component and arhenium component. Still another object is to provide a method ofpreparation of a bismuth-containing trimetallic catalyst which insuresthe bismuth component is in a highly dispersed metallic state during usein the conversion of hydrocarbons.

In brief summary, the present invention is, in one embodiment acatalytic composite comprising a porous carrier material containing, onan elemental basis, about 0.01 to about 2 wt. percent platinum groupmetal, about 0.1 to about 3.5 wt. percent halogen, about 0.01 to about 2wt. percent rhenium and bismuth in an amount sufficient to result in anatomic ratio of bismuth to platinum group metal of about 0.111 to about1:1, wherein the platinum group metal, bismuth and rhenium are uniformlydispersed throughout the porous carrier material and whereinsubstantially all of the platinum group metal, rhenium, and bismuth arepresent in the corresponding elemental metallic states.

A second embodiment relates to a catalytic composite comprising a porouscarrier material containing, on an elemental basis, about 0.05 to about1 wt. percent platinum or palladium or iridium metal, about 0.5 to about1.5 wt. percent halogen, about 0.05 to about 1 wt. percent rhenium, andbismuth in an amount sufficient to result in an atomic ratio of bismuthto platinum or palladium or iridium of about 0.111 to about 0.75:1,wherein substantially all of the platinum or palladium or iridium,rhenium and bismuth are present in the corresponding elemental metallicstates and wherein the metallic ingredients are uniformly dispersed inthe porous carrier material.

Another embodiment relates to a catalytic composite comprising acombination of the catalytic composite described in the first embodimentwith a sulfur component in an amount sufficient to incorporate about0.05 to about 0.5 wt. percent sulfur, calculated on an elemental basis.

Yet another embodiment relates to a process for the conversion ofhydrocarbons comprising contacting the hydrocarbon and hydrogen with thecatalytic composite described above in the first embodiment athydrocarbon conversion conditions.

A preferred embodiment relates to a process for reforming a gasolinefraction which comprises contacting the gasoline fraction andhydrogenwith the catalytic composite described above in the firstembodiment at reforming conditions selected to produce a high-octanereformate.

Other objects and embodiments of the present inven tion relate toadditional details regarding preferred catalytic ingredients, preferredamounts of ingredients, suitable methods of composite preparation,operating conditions for use in the hydrocarbon conversion processes,and the like particulars which are hereinafter given in the followingdetailed discussion of each of these facets of the present invention.

The acidic trimetallic catalyst of the present invention comprises aporous carrier material or support having combined therewithcatalytically effective amounts of a platinum group component, a bismuthcomponent, a rhenium component, and a halogen component Consideringfirst the porous carrier material utilized in the present invention, itis preferred that the material be a porous, adsorptive, high-surfacearea support having a surface area of about 25 to about 500 m /g. Theporous carrier material should be relatively refractory to theconditions utilized in the hydrocarbon conversion process, and it isintended to include within the scope of the present invention carriermaterials which have traditionally been utilized in dual-functionhydrocarbon conversion catalysts such as: (l) activated carbon, coke orcharcoal; (2) silica or silica gel, silicon carbide, clays and silicatesincluding those synthetically-prepared and naturally-occurring, whichmay or may not be acid treated, for example, attapulgus clay, chinaclay, diatomaceous earth, fullers earth, kaoline, kieselguhr, etc.; (3)ceramics, porcelain, crushed firebrick, bauxite; (4) refractoryinorganic oxides such as alumina, titanium dioxide, zirconium dioxide,chromium oxide, zinc oxide, magnesia, thoria, boria, silicaalumina,silica-magnesia, chromia-alumina, aluminaboria, silica-zirconia, etc.',(5) zeolitic crystalline aluminosilicates such as naturally-occurring orsyntheticallyprepared mordenite and/or faujasite, either in the hydrogenform or in a form which has been treated with multivalent cations; (6)spinels such as MgA1 O FeAl- 0 ZnAl O CaAl O, and other like compoundshaving the formula MO-Al O where M is a metal having a valence of 2;and, (7) combinations of elements from one or more of these groups. Thepreferred porous carrier materials for use in the present invention arerefractory inorganic oxides, with best results obtained with a carriermaterial consisting essentially of alumina. Suitable alumina materialsare the crystalline aluminas known as the gamma-, etaand theta-alumina,with gammaor eta-alumina giving best results. In addition, in someembodiments the alumina carrier material may contain minor proportionsof other well known refractory inorganic oxides such as silica,zirconia, magnesia, etc.; however, the preferred support issubstantially pure gamma-, or eta-alumina. Preferred carrier materialshave an apparent bulk density of about 0.3 to about 0.7 g/cc and surfacearea characteristics such that the average pore diameter is about 20 to300 Angstroms,

the pore volume is about 0.1 to about 1 cc/g, and the surface area isabout 100 to about 500 m /g. In general, best results are typicallyobtained with a gammaalumina carrier material which is used in the formof spherical particles having: a relatively small diameter (i.e.typically about 1/16 inch), an apparent bulk density of about 0.5 toabout 0.6 g/cc, a pore volume of about 0.4 cc/g and a surface area ofabout 175 m /g.

The preferred alumina carrier material may be prepared in any suitablemanner and may be syntheticallyprepared or natural occuring. Whatevertype of alumina is employed it may be activated prior to use by one ormore treatments including drying, calcination, steaming, etc., and itmay be in a form known as activated alumina, activated alumina ofcommerce, porous alumina, alumina gel, etc. For example, the aluminacarrier may be prepared by adding a suitable alkaline reagent, such asammonium hydroxide to a salt of aluminum such as aluminum chloride,aluminum nitrate, etc.; in an amount to form an aluminum hydroxide gelwhich upon drying and calcining is converted to alumina. The aluminacarrier may be formed in any desired shape such as spheres, pills,cakes, extrudates, powders, granules, tablets, etc., and utilized in anydesired size. For the purpose of the present invention a particularlypreferred form of alumina is the sphere; and alumina spheres may becontinuously manufactured by the well known oil drop method whichcomprises: forming an alumina hydrosol by any of the techniques taughtin the art and preferably by reacting aluminum metal with hydrochloricacid, combining the resulting hydrosol with a suitable gelling agent anddropping the resultant mixture into an oil bath maintained at elevatedtemperatures. The droplets of the mixture remain in the oil bath untilthey set and form hydrogel spheres. The spheres are then continuouslywithdrawn from the oil bath and typically subjected to specific agingtreatments in oil and an ammoniacal solution to further improve theirphysical characteristics. Theresulting aged and gelled particles arethen washed and dried at a relatively low temperature of about 300 F. toabout 400 F. and subjected to a calcination procedure at a temperatureof about 850 F. to about 1,300 F. for a period of about 1 to about 20hours. This treatment effects conversion of the alumina hydrogel to thecorresponding crystalline gamma-alumina. See the teachings of US. Pat.No. 2,620,314 for additional details.

One essential component of the catalyst of the present invention is therhenium component. It is an essential feature of the present inventionthat substantially all of the rhenium component of the catalyst ispresent therein as the elemental metal, and the hereinafter describedreduction step is specifically designed to reduce this component alongwith the platinum group component and the bismuth component to thecorresponding metallic states. The rhenium component is preferablyutilized in an amount sufficient to result in a final catalyst compositecontaining about 0.01 to about 2 wt. percent rhenium and preferablyabout 0.05 to about 1, calculated on an elemental basis.

The rhenium component may be incorporated in the catalytic composite atany stage in the preparation of the catalyst and in any suitable mannerknown to result in a relatively uniform distribution of this componentin the carrier material such as by coprecipitation, ionexchange orimpregnation. It is generally advisable to incorporate the rheniumcomponent in an impregnation step after the porous carrier material hasbeen formed in order that the expensive metal will not be lost due towashing and purification treatments which may be applied to the carriermaterial during the course of its production. Although any suitablemethod for incorporating a uniform dispersion of a catalytic componentin a porous carrier'material can be utilized to incorporate the rheniumcomponent, the preferred procedure involves impregnation of the porouscarrier material. The impregnation solution can, in general, be asolution ofa suitable soluble, decomposable rhenium salt such asammonium perrhenate, sodium perrhenate, potassium perrhenate, and thelike salts. In addition, solutions of rhenium halides such as rheniumchloride may be used; the preferred impregnation solution is, however,an aqueous solution of perrhenic acid. The porous carrier material canbe impregnated with the rhenium component either prior to,simultaneously with or after the other components mentioned herein arecombined therewith. Best results are ordinarily obtained when therhenium component is impregnated simultaneously with the platinum groupand bismuth components. In fact, excellent results are obtained with aone step impregnation procedure utilizing as an impregnation solution,an aqueous solution of chloroplatinic acid, bismuth trichloride,perrhenic acid, and a strong acid such as hydrochloric'acid, nitric acidand the like.

A second essential ingredient of the subject catalyst is the platinumgroup component. That is, it is intended to cover the use of platinum orpalladium or iridium or rhodium or osmium or ruthenium or mixturesthereof as a second component of the present composite. lt is anessential feature of the present invention that substantially all of theplatinum group component exists within the final catalytic composite inthe elemental metallic state (i.e. as elemental platinum or palladium oriridium, etc.). Generally the amount of the second component used in thefinal composite is relatively small compared to the amount of the othercomponents combined therewith. In fact, the platinum group componentgenerally will comprise about 0.01 to about 2 wt. percent of the finalcatalytic composite, calculated on an elemental basis. Excellent resultsare obtained when the catalyst contains about 0.05 to about 1 wt.percent of platinum, iridium or palladium metal.

This platinum group component may be incorporated in the catalyticcomposite in any suitable manner known to result in a relatively uniformdistribution of this component in the carrier material such ascoprecipitation or cogellation, ion-exchange, or impregnation. Thepreferred method of preparing the catalyst involves the utilization of asoluble, decomposable compound of a platinum group metal to impregnatethe carrier material in a relatively uniform manner. For example, thiscomponent may be added to the support by commingling the latter with anaqueous solution of chloroplatinic, chloroiridic or chloropalladic acid.Other water-soluble compounds of platinum group metals may be employedin impregnation solutions and include ammonium, chloroplatinate,bromoplatinic acid, platinum dichloride, platinum tetrachloride hydrate,platinum dichlorocarbonyl dichloride, dinitrodiaminoplatinum, tetrammineplatinum chloride, palladium chloride, palladium nitrate, palladiumsulfate, etc. The utilization of a platinum group metal chloridecompound, such as chloroplatinic, chloroiridic or chloropalladic acid,is preferred since it facilitates the incorporation of both the platinumgroup component and at least a minor quantity of the halogen componentin a single step. Hydrogen chloride or the like acid is also generallyadded to the impregnation solution in order to further facilitate theincorporation of the halogen component and the uniform distribution ofthe metallic component throughout the carrier material. In addition, itis generally preferred to impregnate the carrier material after it hasbeen calcined in order to minimize the risk of washing away the valuableplatinum or palladium compounds; however in some cases it may beadvantageous to impregnate the carrier material when it is in a gelledstate.

Yet another essential constituent of the trimetallic composite of thepresent invention is a bismuth component. It is an essential feature ofthe present invention that substantially all of this component ispresent in the composite as the elemental metal. That is, it is believedto be a prerequisite for the acquisition of the beneficial effect ofbismuth on a platinum-containing catalyst that the bismuth componentexists in the catalytic composite in the zero oxidation state. All ofthe methods of preparation of the catalytic composite of the presentinvention include a substantially water-free prereduction step which isdesigned to result in the composite containing substantially all of thebismuth component in the elemental metallic state.

The bismuth component may be incorporated into the catalytic compositein any suitable manner known to effectively disperse this componentthroughout the carrier material or to result in this condition. Thus,this incorporation may be accomplished by coprecipitation or cogellationwith the porous carrier material, ionexchange with the carrier materialwhile it is in a gel state, or impregnation of the carrier material atany stage in its preparation. It is to be noted that it is intended toinclude within the scope of the present invention all conventionalmethods for incorporating a metallic component in a catalytic compositewhich results in a uniform distribution of the metallic componentthroughout the associated carrier material. One preferred method ofincorporating the bismuth component into the catalytic compositeinvolves coprecipitating the bismuth component during the preparation ofthe preferred refractory oxide carrier material. Typically, thisinvolves the addition of a suitable, soluble, decomposable bismuthcompound or complex to the alumina hydrosol, and then combining thehydrosol with a suitable gelling agent and dropping the resultingmixture into an oil bath as explained in detail hereinbefore. Afterdrying and calcining the resulting, gelled carrier material, there isobtained an intimate combination of alumina and bismuth oxide, whichcombination has the bismuth component uniformly dispersed throughout thealumina. Another preferred method of incorporating the bismuth componentinto the catalytic composite involves the utilization of a solubledecomposable compound or complex of bismuth to impregnate the porouscarrier material. In general, the solvent used in this preferredimpregnation step is selected on the basis of its capability to dissolvethe desired bismuth compound and is typically an aqueous acidicsolution. Hence, the bismuth component may be added to the carriermaterial by commingling the latter with an aqueous solution of asuitable bismuth salt or water-soluble compound or complex of bismuthsuch as bismuth ammonium citrate, bismuth tribromide, bismuthtrichloride, bismuth trihydroxide, bismuth oxybromide, bismuthoxychloride, bismuth trioxide, bismuth potassium tartrate, bismuthacetate, bismuth oxycarbonate, bismuth nitrate and the like compounds.Best results are ordinarily obtained with a solution of bismuthtrichloride in hydrochloric acid. In general, the bismuth component canbe impregnated either prior to, simultaneously with, or after the othermetallic component is added to the carrier material. However, I haveobtained excellent results by impregnating the bismuth componentsimultaneously with the platinum group component. In fact, I havedetermined that a preferred impregnation solution containschloroplatinic acid, hydrochloric acid, and bismuth trichloride.

Regardless of which bismuth compound is used in the preferredimpregnation step, it is important that the bismuth component beuniformly distributed throughout the carrier material. In order toachieve this objective it is necessary to maintain the pH of theimpregnation solution at a value less than 3, and preferably less than1, and to dilute the solution to a volume which is approximately thesame or greater than the volume of the carrier material which isimpregnated. It is preferred to use a volume ratio of impregnationsolution to carrier material of at least 0.75:1 and preferably about 1:1to about 3:1. or more. Similarly, a relatively long contact time shouldbe used during this impregnation step ranging from about 0.25 hours upto about 0.5 hours or more. The carrier material is likewise preferablyconstantly agitated during this impregnation step.

It is essential to incorporate a halogen component into the trimetalliccatalytic composite of the present invention. Although the precise formof thechemistry of the association of the halogen componentwith thecarrier material is not entirely known, it is customary in the art torefer to the halogen component as being combined with the carriermaterial, or with the other ingredients of the catalyst in the form ofthe halide (e.g. as the combined chloride). This combined halogen may beeither fluorine, chlorine, bromine, or mixtures thereof. Of thesefluorine and, particularly, chlorine are preferred for the purpose ofthe present invention. The halogen may be added to the carrier materialin any suitable manner, either during preparation of the support orbefore or after the addition of the other components. For example, thehalogen may be added, at any stage of the preparation of the carriermaterial or to the calcined carrier material, as an aqueous solution ofa suitable, decomposable halogencontaining compound such as hydrogenfluoride, hydrogen chloride, hydrogen bromide, ammonium chloride, etc.The halogen component or a portion thereof, may be combined with thecarrier material during the impregnation of the latter with the metalliccomponents; for example, through the utilization of a mixture ofchloroplatinic acid, bismuth trichloride and hydrogen chloride. Inanother situation, the alumina hydrosol which is typically utilized toform the preferred alumina carrier material may contain halogen and thuscontribute at least a portion of the halogen component to the finalcomposite. For reforming, the halogen will be typically combined withthe carrier material in an amount sufficient to result in a finalcomposite that contains about 0.l to about 3.5 percent and preferablyabout 0.5 to about 1.5 percent by weight of halogen, calculated on anelemental basis. In isomerization or hydrocracking embodiments, it isgenerally preferred to utilize relatively larger amounts of halogen inthe catalyst typically, ranging up to about 10 wt. percent halogencalculated on an elemental basis, and more preferably about 1 to aboutwt. percent.

Regarding the preferred amounts of the various metallic components ofthe subject catalyst, l have found it to be a preferred practice toselect the amount of the rhenium component to produce a compositecontaining an atomic ratio of rhenium to platinum group metal within thebroad range of about 0.l:l to 3:1, with the most preferred range beingabout 0.1 5:1 to about 1521. Similarly, I have found that it isessential to fix the amount of the bismuth component as a function ofthe amount of the platinum group component contained in the composite.More specifically, I have observed that the beneficial interaction ofthe bismuth component with the platinum group component is only obtainedwhen the bismuth component is present on an atomic basis, in an amountnot greater than the platinum group component. Quantitatively, theamount of the bismuth component is preferably sufficient to provide anatomic ratio of bismuth to platinum group metal of about 0. l :1 toabout 1:1, with best results obtained at an atomic ratio of about 0.l:lto about 0.75:1. The criticalness associated with this atomic ratiolimitation is apparent when an attempt is made to convert hydrocarbonswith a catalyst having an atomic ratio of bismuth to platinum groupmetal of greater than 1:1. in this latter case substantial deactivationof the platinum component is observed. Accordingly, it is an essentialfeature of the present invention that the amount of the bismuthcomponent is chosen as a function of the amount of the platinum groupcomponent in order to inxure that the atomic ratio of these componentsin the resulting catalyst is within the stated range. Specific examplesof especially preferred catalytic composites are as follows: (1) acatalytic composite comprising 0.375 wt. percent platinum, 0.375 wt.percent rhenium, 0.25 wt. percent bismuth, and 0.5 to 1.5 wt. percenthalogen combined with an alumina carrier material (atomic ratio Bi to Pt0.62:1); (2) a catalytic composite comprising 0.375 wt. percentplatinum, 0.2 wt. percent rhenium, 0.15 wt. percent bismuth, and 0.5 to1.5 wt. percent halogen combined with an alumina carrier material(atomic ratio Bi to Pt 0.38:1); (3) a catalytic composite comprising 0.6wt. percent platinum, 0.25 wt. percent rhenium, 0.1 wt. percent bismuth,and 0.5 to 1.5 wt. percent halogen combined with an alumina carriermaterial (atomic ratio Bi to Pt 0.15521); 4) a catalytic compositecomprising 0.375 wt. percent platinum, 0.375 wt. percent rhenium, 0.05wt. percent bismuth and 0.5 to 1.5 wt. percent halogen combined with analumina carrier material (atomic ratio Bi to Pt 0.l26:l); and, (5) acatalytic composite comprising 0.75 wt. percent platinum, 0.5 wt.percent rhenium, 0.4 wt. percent bismuth and 0.5 to 1.5 wt. percenthalogen combined with an alumina carrier material (atomic ratio Bi to Pt0.5:1).

Another significant parameter for the present catalyst is the totalmetals content which is defined to be the sum of the platinum groupcomponent, the bismuth component and the rhenium component, calculatedon an elemental basis. Good results are ordinarily obtained with thesubject catalyst when this parameter is fixed at a value of about 0.15to about 2.5 wt. percent,

with best results ordinarily achieved at a metals loading of about 0.3to about 2 wt. percent.

An optional ingredient for the trimetallic catalyst of the presentinvention is a Friedel-Crafts metal halide component. This ingredient isparticularly useful in hydrocarbon conversion embodiments of the presentinvention wherein it is preferred that the catalyst utilized has astrong acid or cracking function associated therewith for example, anembodiment wherein hydrocarbons are to be hydrocracked or isomerizedwith the catalyst of the present invention. Suitable metal halides ofthe Friedel-Crafts type include aluminum chloride. aluminum bromide,ferric chloride, ferric bromide, zinc chloride, and the like compounds,with the aluminum halides and particularly aluminum chloride ordinarilyyielding best results. Generally, this optional ingredient can beincorporated into the composite of the present invention by any of theconventional methods for adding metallic halides of this type; however,best results are ordinarily obtained when the metallic halide issublimed onto the surface of the carrier material according to thepreferred method disclosed in US. Pat. No. 2,999,074. The component cangenerally be utilized in any amount which is catalytically effective,with a value selected from the range of about 1 to about wt. percent ofthe carrier material generally being preferred.

Regardless of the details of how the components of the catalyst arecombined with the porous carrier material, the final catalyst generallywill be dried at a temperature of about 200 to about 600 F. for a periodof at least about 2 to 24 hours or more, and finally calcined oroxidized at a temperature of about 700 F. to about l,100 F. in an airatmosphere for a period of about 0.5 to about 10 hours to convertsubstantially all of the metallic components to the corresponding oxideforms. Because a halogen component is utilized in the catalyst, bestresults are generally obtained when the halogen contentof the catalystis adjusted during the calcination step by including a halogen or ahalogencontaining compound in the air atmosphere utilized. lnparticular, when the halogen component of the catalyst is combinedchloride, it is preferred to use a mole ratio of 11:0 to HCl of about5:1 to about 100:1 during at least a portion of the calcination step inorder to adjust the final chlorine content of the catalyst to a range ofabout 0.1 to about 3.5 wt. percent.

It is an essential feature of the present invention that the resultantoxidized trimetallic catalytic composite is subjected to a substantiallywater-free reduction step prior to its use in the conversion ofhydrocarbons. This step is designed to insure a uniform and finelydivided dispersion of the metallic components throughout the carriermaterial and to selectively reduce the platinum group, rhenium and thebismuth components to the corresponding metals. Preferably,substantially pure and dry hydrogen (i.e. less than 20 vol. ppm. B 0) isused as the reducing agent in this step. The reducing agent is contactedwith the oxidized catalyst at conditions including a temperature ofabout 800 F. to about 1,200 F., a gas hourly space velocity of about 100to about 5,000 hr. and a period of time of about 0.5 to 10 hourseffective to reduce substantially all of the platinum group, rhenium andbismuth components to the corresponding elemental metallic states. Thisreduction treatment may be performed in situ as part of a start-upsequence if precautions are taken to predry the plant to a substantiallywater-free state and if substantially water-free hydrogen is used.

The resulting reduced catalytic composite may, in some cases, bebeneficially subjected to a presulfiding operation designed toincorporate in the catalytic composite from about 0.05 to about 0.5 wt.percent sulfur, calculated on an elemental basis, in the form of thesulfide. Preferably, this presulfiding treatment takes place in thepresence of hydrogen and a suitable sulfurcontaining and metallicsulfide-producing compound such as hydrogen sulfide, lower molecularweight mercaptans, organic sulfides, disulfides, etc. Typically, thisprocedure comprises treating the selectively reduced catalyst with asulfiding gas such as a mixture of hydrogen and hydrogen sulfide havingabout moles of hydrogen per mole of hydrogen sulfide at conditionssufficient to effect the desired incorporation of sulfur, generallyincluding a temperature ranging from about 50 F. up to about 1,l00 F. ormore. It is generally a good practice to perform this presulfiding stepunder substantially water-free conditions.

According to the present invention, a hydrocarbon charge stock andhydrogen are contacted with a trimetallic catalyst of the type describedabove in a hydrocarbon conversion zone. This contacting may beaccomplished by using the catalyst in a fixed bed system, a moving bedsystem, a fluidized bed system, or in a batch type operation; however,in view of the danger of attrition losses of the valuable catalyst, andof well known operational advantages, it is preferred to use a fixed bedsystem. In this system, a hydrogen-rich gas and the charge stock arepreheated by any suitable heating means to the desired reactiontemperature and then are passed into a conversion zone containing afixed bed of the catalyst type previously characterized. It is, ofcourse, understood that the conversion zone may be one or more separatereactors with suitable means therebetween to insure that the desiredconversion temperature is maintained at the entrance to each reactor. Itis also important to note that the reactants may be contacted with thecatalyst bed in either upward, downward, or radial flow fashion with thelatter being preferred. In addition, the reactants may be in the liquidphase, a mixed liquid-vapor phase, or a vapor phase when they contactthe catalyst, with best results obtained in the vapor phase.

In the case where the trimetallic catalyst of the present invention isused in a reforming operation, the reforming system will comprise areforming zone containing a fixed bed of the catalyst type previouslycharacterized. The reforming zone may be one or more separate reactorswith suitable heating means therebetween to compensate for theendothermic nature of the reactions that take place in each catalystbed. The hydrocarbon feed stream that is charged to this reformingsystem will comprise hydrocarbon fractions containing napthenes andparaffins that boil within the gasoline range. The preferred chargestocks are those consisting essentially of naphthenes and paraffins,although in some cases aromatics and/or olefins may also be present.This preferred class includes straight run gasolines, natural gasolines,synthetic gasolines and the like. On the other hand, it is frequentlyadvantageous to charge thermally or catalytically cracked gasolines orhigher boiling fractions thereof. Mixtures of straight run and crackedgasolines can also be used to advantage. The gasoline charge stock maybe a full boiling gasoline having an initial boiling point of from aboutF. to about F. and an end boiling point within the range of from about325 F. to about 425 F,, or may be a selected fraction thereofwhichgenerally will be a higher boiling fraction commonly referred to as aheavy naphtha for example, a naptha boiling in the range of C to 400 F.In some cases, it is also advantageous to charge pure hydrocarbons ormixtures of hydrocarbons that have been extracted from hydrocarbondistillates for example, straight-chain paraffins which are to beconverted to aromatics. It is preferred that these charge stocks betreated by conventional catalytic pretreatment methods such ashydrorefining, hydrotreating, hydrodesulfurization, etc., to removesubstantially all sulfurous, nitrogenous and water-yielding contaminantstherefrom and to saturate any olefins that may be contained therein.

In other hydrocarbon conversion embodiments, the charge stock will be ofthe conventional type customarily used for the particular kind ofhydrocarbon conversion being effected. For example, in a typicalisomerization embodiment the charge stock can be a paraffinic stock richin C to C normal paraffins, or a normal butane-rich stock, or ann-hexane-rich stock, or a mixture of xylene isomers, etc. In adehydrogenation embodiment, the charge stock can be any of the knowndehydrogenatable hydrocarbons such as an aliphatic compound containing 2to 30 carbon atoms per molecule a C to C normal paraffin, a C to Calkylaromatic, a naphthene and the like. In hydrocracking embodiments,the charge stock will be typically a gas oil, heavy cracked cycle oil,etc. In addition alkylaromatic and naphthenes can be convenientlyisomerized by using the catalyst of the present invention. Likewise,pure hydrocarbons or substantially pure hydrocarbons can be converted tomore valuable products by using the trimetallic catalyst of the presentinvention in any of the hydrocarbon conversion processes, known to theart, that use a dual-function catalyst.

In a reforming embodiment, it is generally preferred to utilize thenovel trimetallic catalytic composite in a substantially water-freeenvironment. Essential to the achievement of this condition in thereforming zone is the control of the water level present in the chargestock and the hydrogen stream which is being charged to the zone. Bestresults are ordinarily obtained when the total amount of water enteringthe conversion zone from any source is held to a level less than 50 ppm.and preferably less than 20 ppm.; expressed as weight of equivalentwater in the charge stock. In general, this can be accomplished bycareful control of the water present in the charge stock and in thehydrogen stream. The charge stock can be dried by using any suitabledrying means known to the art such as a conventional solid adsorbenthaving a high selectivity for water; for instance, sodium or calciumcrystalline aluminosilicates, silica gel, activated alumina, molecularsieves, anhydrous calcuim sulfate, high surface area sodium and the likeadsorbents. Similarly, the water content of the charge stock may beadjusted by suitable stripping operations in a fractionation column orlike device. And in some cases, a combination of adsorbent drying anddistillation drying may be used advantageously to effect almost completeremoval of water from the charge stock. Preferably, the charge stock isdried to a level corresponding to less than 20 ppm. of H 0 equivalent.In general, it is preferred to maintain the water content of thehydrogen stream entering the hydrocarbon conversion zone at a level ofabout to about 20 vol. ppm. of water or less. In the case where thewater content of the hydrogen stream is above this range, this can beconveniently accomplished by contacting the hydrogen stream with asuitable desiccant such as those mentioned above at conventional dryingconditions.

In the reforming embodiment, an effluent stream is withdrawn from thereforming zone and passed through a cooling means to a separation zone,typically maintained at about 25 to 150 F., wherein a hydrogen-rich gasis separated from a high octane liquid product, commonly called anunstabilized reformate. When a superdry operation is desired, at least aportion of this hydrogen-rich gas is withdrawn from the separating zoneand passed through an adsorption zone containing an adsorbent selectivefor water. The resultant substantially water-free hydrogen stream canthen be recycled through suitable compressing means back to thereforming zone. The liquid phase from the separating zone is typicallywithdrawn and commonly treated in a fractionating system in order toadjust the butane concentration, thereby controlling frontend volatilityof the resulting reformate.

The conditions utilized in the numerous hydrocarbon conversionembodiments of the present invention are those customarily used in theart for the particular reaction, or combination of reactions, that is tobe effected. For instance, alkylaromatics and paraffin isomerizationconditions include: a temperature of about 32 F. to about l,000 F. andpreferably about 75 F. to about 600 F.; a pressure of atmospheric toabout 100 atmospheres; a hydrogen to hydrocarbon mole ratio of about0.5:1 to about 20:1 and a LHSV (calculated on the basis of equivalentliquid volume of the charge stock contacted with the catalyst per hourdivided by the volume of conversion zone containing catalyst) of about0.2 hr. to 10 hr.'. Dehydrogenation conditions include: a temperature ofabout 700 to about 1,250 F., a pressure of about 0.1 to about 10atmospheres, a liquid hourly space velocity of about 1 to 40 hr. and ahydrogen to hydrocarbon mole ratio of about 1:1 to 20:]. Likewise,typically hydrocracking conditions include: a pressure of about 500psig. to about 3,000 psig.; a temperature of about 400 F. to about 900F.', a LHSV of about 0.1 hr. to about 10 hr."; and hydrogen circulationrates of about 1000 to 10,000 SCF per barrel of charge.

In the reforming embodiment of the present invention the pressureutilized is selected from the range of about 0 psig. to about 1,000psig., with the preferred pressure being about 50 psig. to about 600psig. Particularly good results are obtained at low pressure; namely, apressure of about 50 to 350 psig. In fact, it is a singular advantage ofthe present invention that it allows stable operation at lower pressurethan have heretofore been successfully utilized in so-called continuousreforming systems (i.e. reforming for periods of about to about 200 ormore barrels of charge per pound of catalyst without regeneration) withall platinum monometallic catalysts. in other words, the trimetalliccatalyst of the present invention allows the operation of a continuousreforming system to be conducted at low pressure (i.e. 100 to about 350psig.) for about the same or better catalyst life before regeneration ashas been heretofore realized with conventional monometallic catalysts athigher pressures (i.e. 400 to 600 psig.). On the other hand, thestability feature of the present invention enables reforming operationconducted at pressures of 400 to 600 psig. to achieve substantiallyincreased catalyst life before regeneration.

Similarly, the temperature requiredfor reforming is generally lower thanthat required for a similar reforming operation using a high qualitycatalyst of the prior art. This significant and desirable feature of thepresent invention is a consequence of the selectivity of the trimetalliccatalyst of the present invention for the octane-upgrading reactionsthat are preferably induced in a typical reforming operation. Hence thepresent invention requires a temperature in the range of from about 800F. to about 1,l00 F. and preferably about 900 F. to about 1,050 F. As iswell known to those skilled in the continuous reforming art, the initialselection of the temperature within this broad range is made primarilyas a function of the desired octane of the product reformate consideringthe characteristics of the charge stock and of the catalyst. Ordinarily,the temperature then is thereafter slowly increased during the run tocompensate for the inevitable deactivation that occurs to provide aconstant octane product. Therefore, it is a feature of the presentinvention that the rate at which the temperature is increased in orderto maintain a constant octane product, is substantially lower for thecatalyst of the present invention than for a high quality reformingcatalyst which is manufactured in exactly the same manner as thecatalyst of the present invention except for the inclusion of thebismuth and rhenium components. Moreover, for the catalyst of thepresent invention, the C yield loss for a given temperature increase issubstantially lower than for a high quality reforming catalyst of theprior art. In addition, hydrogen production is substantially higher.

The reforming embodiment of the present invention also typicallyutilizes sufficient hydrogen to provide an amount of about 1 to about 20moles of hydrogen per mole of hydrocarbon entering the reforming zone,with excellent results being obtained when about 5 to about 10 moles ofhydrogen are used per mole of hydrocarbon. Likewise, the liquid hourlyspace velocity (LHSV) used in reforming is selected from the range ofabout 0.1 to about 10 hr., with a value in the range of about 1 to about5 hr." being preferred. In fact, it is a feature of the presentinvention that it allows operations to be conducted at higher LHSV thannormally can be stably achieved in a continuous reforming process with ahigh quality reforming catalyst of the prior art. This last feature isof immense economic significance because it allows a continuousreforming process to operate at the same throughput level with lesscatalyst inventory than that heretofore used with conventional reformingcatalysts at no sacrifice in catalyst life before regeneration.

The following working examples are given to illustrate further thepreparation of the trimetallic catalytic composite of the presentinvention and the use thereof in the conversion of hydrocarbons. It isunderstood that the examples are intended to be illustrative rather thanrestrictive.

EXAMPLE I This example demonstrates a particularly good method ofpreparing the trimetallic catalytic composite of the present invention.

An alumina carrier material comprising 1/16-inch spheres is prepared by:forming an aluminum hydroxyl chloride sol by dissolving substantiallypure aluminum pellets in hydrochloric acid, addinghexamethylenetetramine to the resulting alumina sol, gelling theresulting solution by dropping it into an oil bath to form sphericalparticles of an aluminum-containing hydrogel, aging and washing theresulting particles and finally drying and calcining the aged and washedparticles to form spherical particles of gamma-alumina containing about0.3 wt. percent combined chloride. Additional details as to this methodof preparing the preferred gammaalumina carrier material are given inthe teachings of US. Pat. No. 2,620,314.

An aqueous impregnation solution containing chloroplatinic acid,perrhenic acid, bismuth trichloride and hydrogen chloride is thenprepared. The alumina carrier material is thereafter admixed with theimpregnation solution. The amount of reagents contained in thisimpregnation solution is calculated to result in a final compositecontaining, on an elemental basis, 0.375 wt. percent platinum, 0.25 wt.percent bismuth and 0.375 wt. percent rhenium. In order to insureuniform dispersion of the metallic components throughout the carriermaterial, the amount of hydrochloric acid used is about 3 wt. percent ofthe alumina particles. This impregnation step is performed by adding thecarrier material particles to the impregnation mixture with constantagitation. In addition, the volume of the solution is approximately thesame as the volume of the carrier material particles. The impregnationmixture is maintained in contact with the carrier material particles fora period of about one-half hour at a temperature of about 70 F.Thereafter, the temperature of the impregnation mixture is raised toabout 225 F. and the excess solution evaporated in a period of about 1hour. The resulting dried particles are then subjected to a calcinationor oxidation treatment in an air atmosphere at a temperature of about975 F. for about 1 hour. This oxidation step is designed to convertsubstantially all of the metallic ingredients to the corresponding oxideforms. The calcined spheres are then contacted with an air streamcontaining H and HCl in a mole ratio of about 30:1 for about 4 hours at975 F. in order to adjust the halogen content of the catalyst particlesto a value of about 1 wt. percent.

The resulting catalyst particles are analyzed and found to contain, onan elemental basis, about 0.375 wt. percent platinum, about 0.25 wt.percent bismuth, about 0.375 wt. percent rhenium and about 1 wt. percentcombined chloride. For this catalyst, the atomic ratio of rhenium toplatinum is 1.05:1 and the atomic ratio of bismuth to platinum is0.62221.

Thereafter, the catalyst particles are subjected to a dry pre-reductiontreatment, designed to reduce substantially all of the platinum, rheniumand bismuth components to the corresponding elemental metallic states bycontacting them for 1 hour with a substantially pure hydrogen streamcontaining less than 5 vol. ppm. H O at a temperature of about 1,050 F.,a pressure slightly above atmospheric, and a flow rate of the hydrogenstream through the catalyst particles corresponding to a gas hourlyspace velocity of about 720 hrf.

EXAMPLE ll A portion of the spherical trimetallic catalyst particlesproduced by the method described in Example 1 are loaded into a scalemodel ofa continuous, fixed bed reforming plant of conventional design.In this plant a heavy Kuwait naptha and hydrogen are continuouslycontacted at reforming conditions: a liquid hourly space velocity of 1.5hrf; a pressure of 100 psig.; a hydrogen to hydrocarbon mole ratio of5:1 and a temperature sufficient to continuously produce a C reformateof 102 F-l clear. It is to be noted that these are exceptionally severeconditions.

The heavy Kuwait naphtha has an API gravity at 60 F. of 60.4, an initialboiling point of 184 F.. a percent boiling point of 256 F., an endboiling point of 360 F. In addition, it contains about 8 vol. percentaromatics, 71 vol. percent paraffins, 21 vol. percent naphthenes, 0.5wt. percent parts per million sulfur, and 5 to 8 wt. parts per millionwater. The F-l clear octane number of the raw stock is 40.0.

The fixed bed reforming plant is made up ofa reactor containing thetrimetallic catalyst, a hydrogen separation zone, a debutanizer column,and suitable heating, pumping, cooling and controlling means. In thisplane, a hydrogen recycle stream and the charge stock are commingled andheated to the desired temperature. The resultant mixture is then passeddownflow into a reactor containing the trimetallic catalyst as a fixedbed. An effluent stream is then withdrawn from the bottom of thereactor, cooled to about F. and passed to a separating zone wherein ahydrogen-rich gaseous phase separates from a liquid hydrocarbon phase. Aportion of the gaseous phase is continuously passed through a highsurface area sodium scrubber and the resulting water-free hydrogenstream recycled to the reactor in order to supply hydrogen thereto, andthe excess hydrogen over that needed for plant pressure is recovered asexcess separator gas. The liquid hydrocarbon phase from the hydrogenseparating zone is withdrawn therefrom and passed to a debutanizercolumn of conventional design wherein light ends are taken overhead asdebutanizer gas and C reformate stream recovered as bottoms.

The test run is continued for a catalyst life of about 20 barrels ofcharge per pound of catalyst utilized, and it is determined that theactivity, selectivity and stability of the present trimetallic catalystare vastly superior to those observed in a similar type test with aconventional commercial reforming catalyst. More specifically, theresults obtained from the subject catalyst are superior to the platinummetal-containing catalyst of the prior art in the areas of hydrogenproduction, C yield at octane, average rate of temperature increasenecessary to maintain octane, and C yield decline rate.

It is intended to cover by the following claims all changes andmodifications of the above disclosure of the present invention whichwould be self-evident to a man of ordinary skill in the catalystformulation art or the hydrocarbon conversion art.

I claim as my invention:

1. A process for converting a hydrocarbon charge stock which comprisescontacting the hydrocarbon charge stock at hydrocarbon conversionconditions with a catalytic composite comprising a porous carriermaterial containing, on an elemental basis, about 0.01 to about 2 wt.percent platinum group metal, about 0.01 to about 2 wt. percent rhenium,about 0.1 to about 3.5 wt. percent halogen and bismuth in an amountsufficient to result in an atomic ratio of bismuth to platinum groupmetal of about 0.1:] to about 1:1, wherein the platinum group metal,rhenium, and bismuth are uniformly dispersed throughout the porouscarrier material and wherein substantially all of the platinum groupmetal, rhenium and bismuth are present in the corresponding elementalmetallic states.

2. A process as defined in claim 1 wherein the platinum group metal isplatinum.

3. A process as defined in claim 1 wherein the platinum group metal ispalladium.

4. A process as defined in claim 1 wherein the platinum group metal isiridium.

5. A process as defined in claim 1 wherein the halogen component iscombined chloride.

6. A process as defined in claim 1 wherein the porous carrier materialis a refractory inorganic oxide.

7. A process as defined in claim 1 wherein the porous carrier materialconsists essentially of alumina.

8. A process as defined in claim 1 wherein the atomic ratio of bismuthto platinum group metal is about 0.1:1 to about 0.75:1.

9. A process as defined in claim 1 wherein the catalytic compositecontains about 0.05 to about 0.5 wt. percent sulfur, calculated on anelemental basis.

10. A process as defined in claim 1 wherein the atomic ratio of rheniumto platinum group metal contained in the composite is about 0.1:1 toabout 3:1.

11. A process as defined in claim 1 wherein the catalytic compositecontains about 0.05 to about 1 wt. percent platinum group metal, about0.05 to about 1 wt.

percent rhenium, about 0.5 to about 1.5 wt. percent halogen and anatomic ratio of bismuth to platinum group metal of about 0.1:1 to about0.75:].

12. A process as defined in claim 1 wherein the contacting of thehydrocarbon charge stock with the catalytic composite is performed inthe presence of hydrogen.

13. A process as defined in claim 1 wherein the type of hydrocarbonconversion is catalytic reforming of a gasoline fraction to produce ahigh-octane reformate, wherein the hydrocarbon charge stock is containedin the gasoline fraction, wherein the contacting is performed in thepresence of hydrogen and wherein the hydrocarbon conversion conditionsare reforming conditions.

14. A process as defined in claim 13 wherein the reforming conditionsinclude a temperature of about 800 to 1,l00 F., a pressure of about 0 toabout 1,000 psig., a liquid hourly space velocity of about 0.1 to about10 hr. and a mole ratio of hydrogen to hydrocarbon of about 1:1 to about20:1.

15. A process as defined in claim 13 wherein the contacting step isperformed in a substantially water-free environment.

16. A process as defined in claim 13 wherein the reforming conditionsinclude a pressure of about 50 to

1. A PROCESS FOR CONVERTING A HYDROCARBON CHARGE STOCK WHICH COMPRISESCONTACTING THE HYDROCARBON CHARGE STOCK AT HYDROCARBON CONVERSIONCONDITIONS WITH A CATALYTIC COMPOSITE COMPRISING A POROUS CARRIERMATERIAL CONTAINING, ON AN ELEMENTAL BASIS, ABOUT 0.01 TO ABOUT 2 WT.PERCENT PLATINUM GROUP METAL, ABOUT 0.01 TO 2 WT. PERCENT RHENIUM, ABOUT0.1 TO ABOUT 3.5 WT. PERCENT HALOGEN AND BISMUTH IN AN AMOUNT SUFFICIENTTO RESULT IN AN ATOMIC RATIO OF BISMUTH TO PLATINUM GROUP METAL OF ABOUT0.1:1 TO ABOUT 1:1, WHEREIN THE PLATINUM GROUP METAL, RHENIUM, ANDBISMUTH ARE UNIFORMLY DISPERSED THROUGHOUT THE POROUS CARRIER MATERIALAND WHEREIN SUBSTANTIALLY ALL OF THE PLATINUM GROUP METAL, RHENIUM ANDBISMUTH ARE PRESENT IN THE CORRESPONDING ELEMENTAL METALLIC STATES.
 2. Aprocess as defined in claim 1 wherein the platinum group metal isplatinum.
 3. A process as defined in claim 1 wherein the platinum groupmetal is palladium.
 4. A process as defined in claim 1 wherein theplatinum group metal is iridium.
 5. A process as defined in claim 1wherein the halogen component is combined chloride.
 6. A process asdefined in claim 1 wherein the porous carrier material is a refractoryinorganic oxide.
 7. A process as defined in claim 1 wherein the porouscarrier material consists essentially of alumina.
 8. A process asdefined in claim 1 wherein the atomic ratio of bismuth to platinum groupmetal is about 0.1:1 to about 0.75:1.
 9. A process as defined in claim 1wherein the catalytic composite contains about 0.05 to about 0.5 wt.percent sulfur, calculated on an elemental basis.
 10. A process asdefined in claim 1 wherein the atomic ratio of rhenium to platinum groupmetal contained in the composite is about 0.1:1 to about 3:1.
 11. Aprocess as defined in claim 1 wherein the catalytic composite containsabout 0.05 to about 1 wt. percent platinum group metal, about 0.05 toabout 1 wt. percent rhenium, about 0.5 to about 1.5 wt. percent halogenand an atomic ratio of bismuth to platinum group metal of about 0.1:1 toabout 0.75:1.
 12. A process as defined in claim 1 wherein the contactingof the hydrocarbon charge stock with the catalytic composite isperformed in the presence of hydrogen.
 13. A process as defined in claim1 wherein the type of hydrocarbon conversion is catalytic reforming of agasoline fraction to produce a high-octane reformate, wherein thehydrocarbon charge stock is contained in the gasoline fraction, whereinthe contacting is performed in the presence of hydrogen and wherein thehydrocarbon conversion conditions are reforming conditions.
 14. Aprocess as defined in claim 13 wherein the reforming conditions includea temperature of about 800* to 1,100* F., a pressure of about 0 to about1,000 psig., a liquid hourly space velocity of about 0.1 to about 10 hr.1 and a mole ratio of hydrogen to hydrocarbon of about 1:1 to about20:1.
 15. A process as defined in claim 13 wherein the contacting stepis performed in a substantially water-free environment.
 16. A process asdefined in claim 13 wherein the reforming conditions include a pressureof about 50 to about 350 psig.